DEVELOPMENT OF ACCELERATED ENVIRONMENTAL EXPOSURE TESTS THAT TARGET SPECIFIC DEGRADATION MECHANISMS

摘要

Given the wide variety of industrial environments that control electronics are exposed to, prevention of all environmental degradation mechanisms during use can be a challenge. Mixed Flowing Gas (MFG) environments have been used for years to understand how a specific electronic component or assembly may perform in harsh industrial environments. The problem is that standardized MFG tests do not accelerate certain corrosion mechanisms found in specific application environments, especially some diffusion rate-controlled mechanisms. Also, in many accelerated tests, the surface corrosion rates on silver and copper coupons may not reflect the corrosion rates of other mechanisms that can occur on the various components and surfaces of a printed circuit board assembly. Rockwell Automation has undergone a long-term study on how to accelerate specific problematic corrosion mechanisms that can occur in various customers' industries. The first stage of the investigation was centered on varying standard gas concentration, temperature, and relative humidity of a typical MFG test to drive specific degradation mechanisms. This testing did not yield the intended results. It was apparent that the chemical structure and synergistic effects of the specific contaminants in these application environments were driving the degradation. Thus, air testing was performed at multiple application sites to identify the contaminants in the environments. Once contaminants were identified, testing was performed to determine which components of the contaminates played a role in the degradation. Testing was then done to identify synergistic effects between contaminants and determine the possible chemical reactions between functional groups. Once active chemical participants were identified, the logistics of how to deliver controlled gas phase concentrations of the contaminants were developed and tested. This article details the processes used to develop several unique accelerated exposure tests.